Download Chapter 12

Spencer A. Rathus
Jeffrey S. Nevid
Chapter 12
Infection and Immunity
Vicki L Boye, PhD • Concordia University – Nebraska
Chapter 12
Infection and Immunity
Learning Outcomes:
 Discuss the nature of infection, types of pathogens, and
the course of infections
 Describe the body’s defenses against infection
 Discuss immunity and immunization
 Describe common infectious diseases
 Discuss the causes, transmission, symptoms, diagnosis,
and treatment of sexually transmitted infections
Infection
• Infectious (communicable) diseases caused by
pathogens which are disease-causing organisms
• Types of pathogens include:
viruses
bacteria
fungi
• Modes of transmission
protozoa
parasitic worms
Microbes & Pathogens
• Most microorganisms are not pathogenic, some
essential to our health and life
• Microbes are either endogenous (originate inside
the body or exogenous (originate outside the body)
• Immune system normally recognizes and destroys
invasive pathogens and rids the body of diseased or
worn-out cells; however when system is
compromised or overrun, infection can occur
Bacteria
• Single cell organisms, live in soil, air, plants, and
animals including humans
 Harmful bacteria release toxins
 Use nutrients from host to reproduce
 Grouped in families: Staphylococci,
Streptococci, Chlamydia, Rickettsiae
 Typically treated with antibiotics; however
some are becoming resistant (MRSA)
 Vaccinations are available for some (DPT)
Viruses
• Contain DNA or RNA, “hijack” the cell
• Some remain dormant for long periods; others
reproduce quickly.
• Enter the body through eyes, nose, skin, mouth,
or genital tract
• Antibiotic treatment is ineffective
• Prevention including immunizations is most
effective in combating
Other Pathogens
Fungi – plant organism (yeasts and mold)
• Infections typically occur on skin
• Ringworm (fungal infection of hair, skin, nails)
• Candida (yeast-like fungus)
• diaper rash, thrush (use of antibiotics)
Protozoa – single-celled aquatic animals
• Malaria and diarrhea – major health problems in tropical
climates and developing countries
Parasitic Worms (helminths) – multi-cellular
• Pinworms, tapeworms, flukes – Flourish in intestines;
• can be round or flat, microscopic to several feet in length
Body’s Defenses
First Line of Defense: Physical and Chemical Barriers
Skin
Cilia
Mucous Membranes
Chemical Defenders
Second Line of Defense: Immune System
Specialized white blood cells
lymphocytes, phagocytes, NK cells
Immune response:
Cell-mediated immunity
Antibody-mediated immunity
Nonspecific immune response
Specific Immune Response
• If nonspecific response cannot destroy antigens,
lymphocytes are recruited.
• T-Cells [Helper T cells, Killer T cells, Suppressor T-Cells]
• B-Cells [produces antibodies, memory cells]
• Lymph nodes
Immunity & Immunization
Innate Immunity: mother’s antibodies in
fetus/newborn, temporary and limited
Acquired Immunity: Develops after birth
Active:
Natural Acquired Active Immunity (NAAI)
Develop naturally after producing antibodies when
infected with the pathogen
Artificially Acquired Active Immunity (AAAI)
Immunizations with weakened or killed pathogen –
body produces antibodies
Passive: injected with antibodies
Immune System Disorders
• Allergies: Hypersensitivity to normally harmless
substances; triggers release of histamine – causing
typical symptoms; anaphylaxis – severe reaction
• Asthma: triggers include allergens, pollutants,
stress
• Autoimmune Disorders: immune system attacks
healthy cells as if they were antigens
Rheumatoid arthritis, lupus, multiple sclerosis
Common Infectious Diseases
 “Common Cold” – over 200 viruses
 Influenza – viral
• 3 families type A, B, C – mutate – need annual flu shot
 Pneumonia – viral or bacterial
• Legionnaire’s Disease – deadly bacterial pneumonia
 Tuberculosis – bacteria
high incidence among IV drug user, homeless, people
with HIV/AIDS
 Lyme Disease – bacteria spread by deer ticks
 Mononucleosis – Epstein-Barr virus
•
More prevalent between 16-30 years of age
Sexually Transmitted Infections
• Transmitted through sexual contact including:
vaginal or anal intercourse, oral sex, transmission
from mother to child during child-birth and
breastfeeding as well as contact with contaminated
items
• Bacterial STIs – can be treated, may be asymptomatic
Gonorrhea
Syphilis
Chlamydia – 2nd most common, can cause PID in women
Sexually Transmitted Infections
Viral STIs – no cure, treatments may provide relief
HIV/AIDS – long period from HIV infection to AIDS
• Transmitted through contaminated blood, semen, vaginal
secretions or breast milk
Genital Herpes
• Transmitted by genital and oral contact
• Infected women higher risk of miscarriage, vaginal birth
dangerous for baby – C-section results
Viral Hepatitis – Hepatitis B, C, D – sexual transmission
• Vaccine available for hepatitis B & D, B is mandated
HPV/Genital Warts
• World’s most common, most will contract in lifetime
• Can progress to genital warts – linked to cervical cancer
• HPV vaccines available for both men and women
Sexually Transmitted Infections
Sexually Transmitted Infections